CN104741371A - Contaminated land remediation method - Google Patents

Abstract

The invention discloses a contaminated land remediation method. The method comprises the following steps: screening soil, cleaning solid substances, washing by selection, performing solid-liquid separation, performing soil detection, performing electric flocculation water treatment, precipitating and performing filter-press solid-liquid separation, wherein in the step of washing by selection, toxic soluble heavy metal ions, pesticides, plant catalytic agents and soluble organic matters in the soil are dissolved in water; and in the electric flocculation water treatment, heavy metal ions and organic matters in the water are converted into solid substances by virtue of electrochemical reaction and are flocculated from the water, so that the heavy metal ions and the organic matters comprising the pesticides, bacteria and viruses in a filter-press aqueous solution are removed. The method disclosed by the invention has the technical effects that the heavy metal ions in cleaning water are effectively removed under the condition that any chemical is not added, the physicochemical characteristics of the original soil are reduced, the full-automatic operation can be realized, the water treatment time is reduced, the remediation efficiency is improved, and the remediation cost is reduced.

Description

A kind of restorative procedure of contaminated land

Technical field

The invention belongs to field of environment protection technical field, be specifically related to contaminated land restorative procedure.

Background technology

Chinese patent literature CN 103861867 A discloses a kind of elution method soil remediation technique on June 18th, 2014, and its step comprises feeding, primary dcreening operation separation, dusting cover separation, the oxidation of sour stirring pool, Separation of Solid and Liquid, reducing metal ion, precipitate metal ion, the organic insoluble matter of flocculation, precipitate and separate and press filtration process.Wherein, primary dcreening operation drip washing, dusting cover drip washing by heavy metal ion and other pollutants be separated to from soil in water; The oxidation of acid stirring pool is by soluble in water after the anion binding in metal ion and acid; Silt and the aqueous solution separate by Separation of Solid and Liquid; Reducing metal ion is reacted to reduce to produce in alkali pond and hydroxyl by the sewage of metal ion to precipitate; Flocculate organic insoluble matter, then after level Four sedimentation basin precipitation, implement Separation of Solid and Liquid by press filtration process.Compared with technology in the past, the speed that the method is administered contaminated soil is fast, can repair a large amount of soil, be applicable to the soil remediation of heavy metal and Organic Pollution.

But, the method has the following disadvantages: the composition 1, owing to may participate in acid reaction in earth is a lot, acid adding in the sour stirring pool of muddy water mixing, because of chemical balance factor, excessive acid certainly will be added, this may cause soil acidity, eliminates the multiple soil constituent that non-heavy metal pollutes simultaneously, comprises the prototroph composition forming soil; 2, the material owing to participating in acid reaction is many, so the solid matter that alkali reaction and flocculation produce afterwards is many, namely subsequent step is by dangerous solid waste a large amount of for process; 3, the earth after Separation of Solid and Liquid and water all must add alkali adjustment PH to original value, and this is by the processing cost of more increase technique and medicine; 4, the method is difficult to the agricultural chemicals, plant growth substance etc. that significantly remove contaminated land; 5, the composition transfer of rehabilitating soil, original physicochemical characteristic may be caused to change by this PROCESS FOR TREATMENT, fertility is lost, and processing cost is high simultaneously, and treatment effeciency is low.

Summary of the invention

For the technical problem existed in prior art, technical problem to be solved by this invention is just to provide a kind of restorative procedure of contaminated land, do not need to add chemicals, it can simply, fast by pollutant removals such as the heavy metal of contaminated soil, agricultural chemicals, plant growth substances, recover the original physicochemical characteristic in soil; Reach national related land repairing standard, and soil can be carried out the adjustment of formula in soil according to new planning purposes; Technique simplifies, treatment effeciency is high, and soil is selected wash water for a post and all recycled, and does not have the secondary pollution in soil, with low cost, effectively can solve the large-scale pollution amelioration problem in soil.

Technical problem to be solved by this invention is realized by such technical scheme, comprises the following steps:

Step 1, screening earth: sieve in earth, isolate bulk solid thing and loose earth;

Step 2, cleaning bulk solid thing: the solids of isolated bulk in automatic water cleaning step 1, the water filtered out after cleaning is delivered to step 3 and is selected scouring water for a post as earth, and the solids of the bulk after cleaning concentrates landfill, or sorting utilizes further;

Step 3, select for a post and wash earth: loose earth step 1 sieved out is sent to and selected the machine of washing for a post, carry out stirring and select for a post and wash, become dispersion mud selecting dry earth in machine, make solvable heavy metal, agricultural chemicals, Plant growth accelerator and dissolved organic matter in earth soluble in water;

Step 4, Separation of Solid and Liquid: the mud of step 3 is carried out continuous filtration, obtain solid-state earth and filtering solution;

Step 5, Soil K+adsorption: detect pollutant load in the solid-state earth after step 4 processes, as below standard, then send in step 3 to select for a post and wash, as up to standard, then backfill;

Step 6, electricity flocculation water treatment: the filtering solution after step 3 processes is sent into electric flocculation plant and carried out continuous electrochemical process, the solids that heavy metal ion and organic matter are generated by electrochemical reaction is flocculated out from water, the heavy metal ion of removing filtering solution and organic matter, comprise agricultural chemicals, bacterium, virus etc.;

Step 7, precipitation: the water through electrochemical treatments is sent into tube settler, and after precipitation, top layer clear water direct reuse is in step 2 and step 3;

Sediment press filtration in step 8, inclined tube: the sediment in inclined tube of sedimentation tank is carried out the process of press filtration Separation of Solid and Liquid, and by the Water circulation of separation in step 2 and step 3, solid is used as the useless rubbish of danger and is sent into the professional processed in units of the useless process of corresponding danger.

Compared with prior art, the present invention, to containing the serious earth of heavy metal, can repeat fast to select for a post to wash, until up to standard between step 3 to step 5; The present invention utilizes electric flocculation technique to remove the heavy metal be dissolved in water, and does not add any chemicals, does not have secondary pollution problem, the physicochemical characteristic of reduction initial soil that can be best; The present invention can not only remove the heavy metal in soil, can also remove the soil chemistry pollutants such as agricultural chemicals in soil and plant growth substance simultaneously; Different from patent document CN 103861867 A technique, because the present invention does not carry out acidic oxidation to slime water, in water treatment, also eliminate the reducing metal ions in alkali pond and precipitate metal ion two steps, and the water after process is tending towards PH neutrality naturally; The present invention is because have employed electricity flocculation water treatment facilities, and processing speed increases substantially, and process one case sewage only uses 4-10 minute usually, and therefore whole soil remediation efficiency significantly promotes; The present invention obtains water through step 7, step 8, completely for step 2 or step 3, therefore selects wash water for a post and is recycled completely; The present invention because not adding any chemicals in processed water, pollutant is by the hydrogen ion that produces voluntarily under electric field action and hydroxide ion oxidation or reduction, be flocculated and air supporting simultaneously, so the solid-state danger waste sludge produced significantly reduces, usually reduce 2/3-1/2 than chemical method process; Present invention process process can be designed as full automation and runs, and operating cost prime cost is the electricity charge, repairs every cubic metre of soil grid electricity fee cost and is no more than 20 yuan, therefore can significantly Economization on land rehabilitation cost.

Accompanying drawing explanation

Accompanying drawing of the present invention is described as follows:

Fig. 1 is the flow chart of this method invention.

Detailed description of the invention

Below in conjunction with drawings and Examples, the invention will be further described.

Embodiment

As shown in Figure 1, the present invention includes following steps:

1, earth is sieved: fetch earth and detect containing soluble ion state crome metal 550mg/kg, first from earth, sieve out bulk solid thing, bulk solid thing refers to presumable stone, plastics, rubber, glass, metal, brick and tile, wood, battery etc. in earth;

2, bulk solid thing is cleaned: by the solids of bulk isolated in step 1, deliver on the conveyer belt of screen cloth, the cleaning automatically of conveying limit, limit spray, the water that screen cloth leaches and silt particle are delivered to step 3 and are selected scouring water for a post as earth, the solids of the bulk after cleaning is concentrated and is stacked or landfill, or sorting utilizes further;

3, select for a post and wash earth: loose earth step 1 sieved out is sent to and selected the machine of washing for a post, carry out stirring by water-solid ratio 5:1 to select for a post and wash, become the mud be dispersed in water selecting dry earth in the machine of washing for a post, make solvable heavy metal chromium ion, agricultural chemicals, Plant growth accelerator and dissolved organic matter in earth soluble in water, stirring is selected for a post and is washed 3-5 minutes, delivers to solid-liquid separating machine;

4, Separation of Solid and Liquid: the mud of step 3 is carried out continuous filtration, seperator adopts continuous centrifuge or filter press; Obtain solid-state moisture earth and press filtration water;

5, Soil K+adsorption: being detected the solid-state earth content of chromium ion leached is 245mg/kg, this is because although chromium ion has dissolved in water, filter can not thoroughly leach the water selected for a post and wash earth, in residue water, contained chromium ion can still remain in earth.According to new national standard " exhibition land used evaluation criteria of soil environment quality (provisional) HJ350-2007 " requirement, A is designated as chromium ion≤190mg/kg, therefore once select for a post wash defective.Again step 4 is filtered the solid-state moisture earth obtained all to send in step 3 to select for a post and wash and step 4 Separation of Solid and Liquid, again being detected the solid-state earth content of chromium ion leached is 136mg/kg, through to select for a post for twice wash up to standard, can by solid puree earthen backfill up to standard in soil;

6, electricity flocculation water treatment: the whole filtered water after step 3 processes send into electric flocculation plant, carry out continuous electrochemical process, the parameter such as voltage, electric current, pole plate, time adopting electric flocculation apparatus to specify, by organic matters such as the chromium heavy metal ion in water and agricultural chemicals, the solids generated by electrochemical reaction flocculates out from water, and the electrochemical reaction time is 7 minutes;

7, precipitate: the water through electrochemical reaction process is sent into tube settler, get top layer clear water after precipitation to detect, to record content of chromium ion be 0-5mg/kg, COD is less than 56, BOD is 5, show the organic matters such as heavy metal, agricultural chemicals such as the chromium ion in water, comprise bacterial virus and be all removed, whole top layers clear water direct reuse is in step 2 and step 3;

8, sediment press filtration in inclined tube: the sediment in inclined tube of sedimentation tank is carried out the process of press filtration Separation of Solid and Liquid, and by the Water circulation of separation in step 2 and step 3, solid is used as the useless rubbish of danger and is sent into the professional processed in units of the useless process of corresponding danger.

Claims (1)

1. a restorative procedure for contaminated land, its feature comprises step:

Step 1, screening earth: sieve in earth, isolate bulk solid thing and loose earth;

Step 2, cleaning bulk solid thing: the solids of isolated bulk in automatic water cleaning step 1, the water filtered out after cleaning is delivered to step 3 and is selected scouring water for a post as earth, and the solids of the bulk after cleaning concentrates landfill, or sorting utilizes further;

Step 3, select for a post and wash earth: loose earth step 1 sieved out is sent to and selected the machine of washing for a post, carry out stirring and select for a post and wash, become dispersion mud selecting dry earth in machine, make solvable heavy metal, agricultural chemicals, Plant growth accelerator and dissolved organic matter in earth soluble in water;

Step 4, Separation of Solid and Liquid: the mud of step 3 is carried out continuous filtration, obtain solid-state earth and filtering solution;

Step 5, Soil K+adsorption: detect pollutant load in the solid-state earth after step 4 processes, as below standard, then send in step 3 to select for a post and wash, as up to standard, then backfill;

Step 6, electricity flocculation water treatment: the filtering solution after step 3 processes is sent into electric flocculation plant and carried out continuous electrochemical process, the solids that heavy metal ion and organic matter are generated by electrochemical reaction is flocculated out from water, the heavy metal ion of removing filtering solution and organic matter, comprise agricultural chemicals, bacterium, virus etc.;

Step 7, precipitation: the water through electrochemical treatments is sent into tube settler, and after precipitation, top layer clear water direct reuse is in step 2 and step 3;

Sediment press filtration in step 8, inclined tube: the sediment in inclined tube of sedimentation tank is carried out the process of press filtration Separation of Solid and Liquid, and by the Water circulation of separation in step 2 and step 3, solid is used as the useless rubbish of danger and is sent into the professional processed in units of the useless process of corresponding danger.